How To: Build a Porch

A porch is simply a deck with a roof on it, right? Not quite. While some porches may be as simple as that, many are more similar to an indoor room that is missing windows and walls.

Porches typically have more finished flooring than decks. And porch ceilings, while often made of wood, also have a finished look. In fact, just about every aspect of a porch is more finished than its cousin, the deck.

For instance, a porch’s supporting posts are structural as well as decorative. These posts can be columns or boxed-in 4 x 4s with bases and capitals fashioned from molding. Balustrades and knee walls are also porch design mainstays, and these are typically finished with paint, shingles, or stucco.

Another distinction between porches and decks: You can furnish a porch with pieces that wouldn’t stand up to a direct assault from the elements. Wooden tables and chairs, wicker (the real stuff), and upholstered furniture will all fare better on a porch than they would on a deck.

Choosing the Location
Porches are wonderful, so long as they do not cause problems with the rest of the house. The biggest issue homeowners run into when considering a porch addition is related to daylight. A back porch may significantly reduce daylight in the kitchen, or a front porch could cut off daylight to the living room. Take pains to ensure that adding a porch will not darken a portion of the existing house.

Building the Porch
Porches may be built in a wide variety of ways. Let the architecture of your home be your guide. If your house relates to a historical period, study examples of porch styles that were built during that time. You can do this by looking at actual houses or by researching in old magazines and architectural history books.

Porch foundation. Illustration: Inspectapedia.com

Foundations: Some porches are built upon slabs over compacted gravel. The finished floor can be stone, brick, or tile. Other porches are wood-framed and supported by piers and beams. With the latter, the floorboards are typically narrow tongue-and-groove planks that look more like interior strip floors than decking. No matter which type of flooring you choose, the pitch or slope of the floor should run away from the house so that windblown rain and snowmelt can drain before causing damage.

Stairs: Porch stairs can be built with concrete block and veneered with stone or brick, or they can be built of wood. Unlike deck steps, they often have bull nose treads and risers.

Skirting: The space around the porch should be protected with sturdy lattice skirting, or else critters will be vying to dig their burrows in the nice, dry place you’ve created. Include an access door so you can get inside as needed.

Balustrades: Balustrades, or railings, should be designed to match the style of the house. (Don’t use turned balusters on a 1960s ranch!) Solid knee walls may also be used, and these should also be finished to match the house. For example, if the house is sided with clapboard, so should the knee wall.

HBG Porch Columns. Photo: Building Products News

Columns: On the right porch, columns can look very graceful. Be careful with proportions, though. Too narrow and the porch will look insubstantial. Too wide and the porch will look pretentious. Column bases made of wood should be raised slightly off the floor to prevent rot. (For the same reason, column shafts should be ventilated at top and bottom.) Pressure-treated posts clad with PVC boards and moldings are an alternative.

Roofs: Porch roofs, whether shed or gable-style, usually have a shallow slope. This is because they attach to the house at the top of the first floor (or maybe a bit higher on a two-story home), and because the porch eave must allow for adequate headroom. The exception, of course, is when the porch is integrated into the house design from the start, in which case there is often living space above the porch.

A porch is a wonderful place to spend time. Just be sure to spend a little extra time designing and planning for it, before you begin construction.